A data transmission system typically includes a number of integrated circuits (ICs). Data is communicated between the ICs in a data transmission system through transmission links that are external to the ICs. One or more data signals may be transmitted from a transmitter in one integrated circuit in a data transmission system to a receiver in another integrated circuit in the system through the transmission links. Each of two integrated circuits in a data transmission system may include a transmitter and a receiver to support two-way communication between the ICs.